The present invention relates to a conic fluid bearing, and to a head drum and spindle motor each including the same.
Fluid bearings are installed in places requiring high-speed rotation, such as, a disk driving spindle motor of a hard disk, a rotary polygonal mirror driving motor of a laser printer, a head drum driving spindle motor of a VCR, since fluid bearings provide secure and stable rotation at high speed rotations.
FIG. 1 shows a head drum 1 on which a fluid bearing 2 is installed according to the prior art, and FIG. 2 is a detailed drawing showing the configuration of the fluid bearing. Referring to FIGS. 1 and 2, a hemispherical fluid bearing 2 used in the head drum 1 is comprised of a bush 3, an upper hemisphere 4, a lower hemisphere 5 and a spacer 6.
The bush 3 is cylindrical, and hemispherical cavities 8 and 8' are formed on the upper and lower portions thereof to be respectively combined with the upper and lower hemispheres 4 and 5. A bush hole 7 is formed between the hemispherical cavities 8 and 8'. Through holes 9 and 9' having a smaller diameter than that of the bush hole 7 are formed through the upper and lower hemispheres 4 and 5.
The bush 3 is fixed to a rotary transformer 101 connected to a rotating upper drum 100 such that it rotates together with the upper drum 100. The upper and lower hemispheres 4 and 5 are compressedly fixed to a shaft 11 of a stationary fixed drum 102. The upper and lower hemispheres 4 and 5 are inserted to combine with the hemispherical cavities 8 and 8' formed on the bush 3, and the spacer 6 fits with the shaft 11 between the upper and lower hemispheres 4 and 5 and is situated in the bush hole 7.
In order to manufacture the fluid bearing 2 to be used in a head drum as described above, the bush 3 and the upper and lower hemispheres 4 end 5 are processed through machining, and the hemispherical cavities 8 and 8' in the bush 3 are ground using a lapping machine and then assembled. Also, the hemispherical cavities 8 and 8' and the upper and lower hemispheres 4 and 5 must be precisely processed. Therefore, machining is difficult, and it takes many hours to process. Furthermore, since the spacer 6 must be assembled to be situated in the bush hole 7 between the upper and lower hemispheres 4 and 5, it is difficult to set the size accurately. These disadvantages result in deterioration of productivity.